Known patents of the prior art did not recognize the need to prevent structural failures during hurricanes and primarily were directed to signal viewing stability and housing electrical connections and removability for storm avoidance, maintenance, and repair. Structural references, if any, were directed to gravitational loads specific to weight only.
For structural stability, as an example, the prior art used small extruded ribs to prevent the collar and the signal from “tipping or rocking” during winds. The initial prior art not having a previous experience with disconnect structural failures, especially in non-hurricane regions, could not anticipate the future failures due to hurricane force winds. The still in use today “rib” portions were primarily designed for signal stability to increase visibility during winds having a velocity that can still be safely driven in.
The purpose and function of the “ribs” can also be found in the later art, where “four diagonal grooves” were added as a means to prevent the movement the earlier art described. All other known prior art does not anticipate movement during wind events, but instead described “upwardly” directed forces on the traffic signal while servicing, and also described the structural requirements specific to supporting the signal's weight, with no mention or description of any type of wind loads. A furtherance as to no prior art anticipation of structural failures due to hurricanes can be found specific where such phrases as: “in hurricane prone areas it is often necessary or desirable to remove the signal lights from the hanger and terminal disconnect housing,” “supported connection and which is also adapted to be quickly removed from the hanger and terminal (housing) box during inclement weather.” A manufacturer of the prior art's disconnect housing, regarding the disconnect housing, in a letter to Florida's Department of Transportation stated . . . “not designed to withstand hurricane force wind forces . . . ,” “ . . . never been tested or expected to support hurricane wind forces . . . ,” “ . . . the breakage was with the disconnects . . . ” and “ . . . the majority of the damaged disconnects broke at the bottom, where the hub is located . . . ,” specific to all “ribbed” and “grooved” portions as described in all known prior art.
As previously stated, the art's patents all have almost identical structural designs that are historically proven to fail due to the inventors not anticipating or understanding structural failures of disconnect housings due to hurricanes.
Both the earlier devices provided limited space inside the housings for electrical components and actual space to perform the electrical work. As the U.S. population increased (from the 1960's) large intersections requiring more electrical components compounded the already limited space provided in the prior art devices.
To overcome this deficiency, later art disclosed a larger, rectangular disconnect housing that had two doors for access and added size for room to perform the electrical connections. Though an improvement for operation, the new design of disconnect housings actually was proven historically to experience extremely high quantities of structural failures during hurricanes.